In the presence of these same basic resins, organic disulphides and polysulphides of low sulphur order can be converted into polysulphides of higher sulphur order by reaction with sulphur. Similarly, in the presence of these same basic resins, organic polysulphides of high sulphur order can be converted into polysulphides of lower sulphur order by reaction with mercaptans.
Thus, patent application EP-A-337,837 teaches the preparation of organic disulphides and polysulphides catalysed by organic anion exchange resins containing tertiary amine or quaternary ammonium functional groups (active in hydroxide form). Such resins, generally in the form of grains or beads which are insoluble in liquid reaction media and are thus easy to separate out at the end of the reaction, allow organic disulphides and polysulphides to be obtained by reaction of elemental sulphur with mercaptans and also allow organic polysulphides of high sulphur order to be obtained by reaction of elemental sulphur with organic polysulphides of lower sulphur order.
According to patent application FR 2,742,144, the use of basic resins containing a primary amine function makes it possible, when compared with resins containing a tertiary amine function, to obtain a better degree of conversion of the reactants and/or a faster rate of reaction.
Similarly, patent application FR 2,742,145 recommends the use of strongly basic resins containing a guanidine or amidine function, which also makes it possible, when compared with resins containing a tertiary amine function, to obtain a better degree of conversion of the reactants and/or a faster reaction rate.